Just4kicks247

I have this orangeish sludge mixing in my coolant reservoir and overflowing. Does anyone know what this could be? I originally thought head gasket but no coolant in oil and combustion test was negative. Then I thought transmission cooler but no coolant in transmission. Any thoughts?

digitaltrucker

year, make model? Pics?

Just4kicks247

97 F150 4.6L 4x4

KSBV

Could be anything from normal to old coolant to who knows. I'd flush and replace to start with if that hasn't been done recently. See link for things from others who have seen the same.

http://www.fordf150.net/forums/viewtopic.php?t=102747

Just4kicks247

I flushed it once already after it did coolant was clean and thin like normal coolant. As soon as I started the truck with in a few min it is building up this thick oily orange sludge until it builds up and overflows so something is getting into the cooling system. However I'm not sure where it's coming from.

JCR 56

It does look a little like transmission fluid.

btexan

There are two types of antifreeze, if you mix them you get the sludge, System needs a serious flush then refill.

lewissa81

That's what it looks like to me too. Plus rust from inside cooling system.

Just4kicks247

I flushed the system then refilled it with just water to test and within 5 min I have the sludge building up in reservoir.

lewissa81

How did you flush it?